Accompanied by IT security technologies, portable devices using crypto chip as the major component have witnessed an extensive application. However, crypto chip may disclose varied physical information associated with the data to be processed in case of encryption algorithm, such as energy consumption, electromagnetic radiation and runtime. Such physical information might be used by attackers for Side Channel Attack (SCA) on the crypto chip to snatch the password. Differential Power Analysis (DPA) is a simple and efficient SCA attack approach, which can significantly reduce the validity of the crypto chip. In recent years, scholars have put forward numerous technologies on defending against DPA attack, such as Dual-voltage Single-rail Dynamic Logic (DSDL), Masked Dual-Rial Pre-charge Logic (MDPL) and Sense Amplifier Based Logic (SABL). DSDL evaluation speed is slow due to the lack of corresponding pull-down network; As pointed out in the literature: “Yu Jingchao, Yan Yingjian, Wu Xuetao and etc. Study of Anti-Power-Attack Logic Circuit [J]. Microelectronics, 2015(4):497-501.”, MDPL will have a poor performance in defending against DPA attack in case of postponement deviation to input signals. SABL has gradually become a common approach for defending against DPA attack owing to such features as high working speed and excellent performance in defending against DPA attack.
The shift register is a part used to execute logic operation or store information, which is widely applied to the digital encryption system. As indicated by studies, shift register is one of parts with high energy consumption in the encryption system; meanwhile, as it aims to process data when the clock edge is approaching, its working sequence variation is relatively fixed and easy for identification as compared with other parts; therefore, its energy consumption is normally taken as the analysis point for deciphering conventional crypto chip during differential power analysis.
On this account, it is of vital importance to design a shift register with excellent constant power consumption to defend against DPA attack based on proper logic function.